This invention relates to continuous fastener products and methods and apparatus for forming them.
The use of so called xe2x80x9chook and loopxe2x80x9d fasteners has become exceedingly prevalent in consumer, industrial and medical applications, and virtually any other situations in which fastening is necessary. Such fastening materials are often advantageously manufactured in continuous strip-form to gain various economies inherent in continuous manufacturing techniques and for convenient shipment and storage in roll form for later use. Methods of continuous manufacture frequently result in continuous fastener products having certain directional characteristics, i.e., features associated with their direction of continuous manufacture (xe2x80x9cmachine directionxe2x80x9d) which are distinct from features perpendicular to their direction of continuous manufacture (xe2x80x9ccross-machine directionxe2x80x9d).
While the use of continuously manufactured fastener products is desirable for numerous fastener applications, in some instances the xe2x80x9cas-manufacturedxe2x80x9d direction of the directional features associated with the manufacturing process is less desirable than other possible directional feature orientations. The ability to transform the directional orientation of these directional features to a more desirable direction during continuous manufacture of the fastener product is highly advantageous.
The invention features a novel method of reorienting directional characteristics of a continuously manufactured fastener product to a more desirable direction. The invention also features a novel continuously manufactured fastener product with reoriented directional characteristics.
In one aspect the invention provides a method of forming a fastener product having an array of individual fastener elements extending from a sheet-form base, the fastener elements adapted to engage mating elements for releasable fastening. The method includes the steps of forming a continuous pre-form product having a planar base defining longitudinal edges and an array of fastener elements extending from the base; joining the longitudinal edges of the pre-form product to form a tube having a seam defined by the joined longitudinal edges; and severing the tube across the seam to form the fastener product with segments of seam extending between longitudinal edges of the fastener product.
Variations of this aspect of the invention may include one or more of the following additional features. The step of forming the pre-form product includes continuously extruding resin and continuously molding the resin to form the array of fastener elements integrally with a surface of the pre-form product. The fastener elements of the pre-form product are molded fastener elements overhanging the base to define an overhang direction, the overhang direction in the fastener product extending at least obliquely toward one of the longitudinal edges of the fastener product. The overhang direction of the molded fastener elements in the fastener product extend perpendicular to the longitudinal edges of the fastener product. The base of the pre-form product has a widthwise elastic region corresponding to a longitudinally elastic region in the fastener product. The step of forming the pre-form product includes introducing a sheet-form, uni-directionally elastic material to a pressure gap defined against a rotating mold roll, the uni-directionally elastic material having widthwise elasticity and being longitudinally inelastic to form the widthwise elastic region of the base of the pre-form product corresponding to the longitudinally elastic region in the fastener product. The uni-directionally elastic material includes at least one surface of exposed loop material engageable by the fastener elements. The base of the fastener product is resiliently elastic within its plane. The fastener elements are hook-shaped. The step of severing comprises severing the tube to form a sheet-form fastener product, then slitting the sheet-form fastener product to form multiple continuous strips of fastener product. The step of severing comprises severing the tube along a helical path. The step of joining comprises wrapping the pre-form product to form a tube with opposite longitudinal edges of the pre-form product joined to form a helical seam about the tube; the step of severing including severing the tube along a longitudinal path to form the fastener product. The step of forming the pre-form product further includes shaping selvedge portions along the longitudinal edges of the pre-form product to facilitate joining the longitudinal edges to form the tube.
In another aspect, the invention provides a method of forming a strip-form fastener product having an array of individual fastener elements extending from a continuous base with the fastener elements being adapted to engage mating elements for releasable fastening. The method includes the steps of molding a continuous pre-form product having a planar base and an array of fastener elements extending from the base, the fastener elements overhanging the base to define an overhang direction; joining the longitudinal edges of the pre-form product to form a tube; and severing the tube to form the strip-form fastener product with the overhang direction of the fastener elements extending toward a longitudinal edge of the strip-form fastener product.
Variations on this aspect of the invention may include one or more of the following features. The step of severing includes severing the tube along a helical path. The step of joining includes wrapping the pre-form product to form a tube with opposite longitudinal edges of the pre-form product joined to form a helical seam about the tube; the step of severing comprising severing the tube along a longitudinal path to form the fastener product.
In another aspect, the invention provides a continuous strip-form fastener product of finite width and having two longitudinal edges, the product including a series of joined pre-form tape segments, each having a planar base with opposite machine direction edges extending between longitudinal edges of the product, and an array of fastener elements extending from the base and arranged in rows parallel to the machine direction edges, adjacent tape segments permanently joined along seams at their machine direction edges.
Variations on this aspect of the invention may include one or more of the following additional features. The array of fastener elements includes rows of molded hooks, each hook having a head overhanging the base in a direction parallel to the machine direction edges of the pre-form tape segments and a direction extending toward a longitudinal edge of the fastener product. The pre-form tape segments further include elastic zones having resiliency in a direction transverse to the machine direction edges of the pre-form tape, the elastic zones forming zones of increased longitudinal elasticity in the strip-form fastener product. At least one-surface of the elastic zones includes a loop material engageable by the fastener elements.